Eyespot

From Conservapedia

D. E. Nilsson and S. Pelger [2] used computer modeling of the evolution of eyes to find out if it was possible for there to be a smooth gradient of change from a pigmented eye spot to an eye with a lens and cornea, and how long such a transformation would take. They used highly conservative figures for the possible change in each generation. Many human traits are over 50% heritable, and they gave their model a lower figure. They also chose very conservative values for the amount of possible variation in a population. Using these figures, they calculated that through the mechanism of evolution an eyespot could evolve into an eye with a lens and a cornea in less than a half a million years.

This scenario is contested by Young Earth Creationists, who point out that the scenario begins with a highly-complex structure, and doesn't include the supporting neural structures, without which the eye would be useless.[3]